INVESTIGADORES
ALBARRACIN ORIO Andrea Georgina
congresos y reuniones científicas
Título:
Effect of pbp mutations on cell morphology and growth rate in Streptococcus pneumoniae
Autor/es:
ALBARRACIN ORIO, A; CORTES P; PIÑAS G; ECHENIQUE J
Lugar:
Mar del Plata-Buenos Aires, Argentina
Reunión:
Congreso; XLIII Annual Meeting Argentine Society for Biochemistry and Molecular Biology (SAIB); 2007
Institución organizadora:
Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular
Resumen:
B-Lactam (BL) resistance in S. pneumoniae is caused by mutations in penicillin-binding proteins (PBPs), mainly PBP1a, PBP2x, and PBP2b, which are enzymes involved in cell wall synthesis. Here, we assessed the impact of pbp mutations on cell shape and growth rate. In addition, we used a fluorescent derivative of vancomycin (Fl-Van) as a probe for nascent peptidoglycan synthesis to evaluate the septal and equatorial pattern by fluorescence microscopy. The pbp1a, pbp2b, and pbp2x genes from BL-resistant isolates were transformed into Cp1015, and the transformants were analyzed. All pbp2b mutants showed growth retardation, morphological alterations and simultaneous parallel septal and equatorial staining by Fl- Van, but no such differences could be detected in pbp1a or pbp2x mutants. Because no alterations were observed in the original BL-resistant strains, we constructed double and triple mutants to analyze if pbp genes association may compensate growth rates and cell shape alterations in the pbp2b mutants. The double pbp2b/2x or pbp2b/1a mutants resulted only in a partially restored morphology whereas the triple pbp2b/2x/1a mutant was similar in morphology, growth rate and Fl-Van staining to Cp1015. Our results suggest that acquisition of pbp2x/pbp1a mutations by horizontal transfer have compensatory effects on growth and shape alterations, in addition to development of BL resistance.